Silica supported polymerization catalyst system

ABSTRACT

A new catalyst component useful in the polymerization of at least one olefin is disclosed. The catalyst component comprises the product obtained by contracting silica, in random order, with (1) at least one hydrocarbon soluble magnesium-containing compound; and (2) a first modifying compound selected from the group consisting of silicon halides, boron halides, aluminum halides and mixtures thereof followed by a second modifying compound selected from the group consisting of halides having the structural formula SiH r  X 2   s , where X 2  is halogen; r is an integer of 1 to 3; and s is an integer of 1 to 3 with the proviso that the sum of r and s is 4, a hydrogen halide and mixtures thereof. The product of this step is contacted with a titanium-containing compound having the structural formula TiX 1   p  (OR 1 ) q , where X 1  is halogen; R 1  is hydrocarbyl; p is an integer of 1 to 4; and q is 0 or an integer of 1 to 3, with the provisos that the sum of p and q is 4 and that a second titanium-containing compound having the structural formula Ti(OR) m  X n , where R is hydrocarbyl; X is halogen; m is an integer of 1 to 4; n is 0 or an integer of 1 to 3; and the sum of m and n is 4, is not utilized in the formation of said catalyst component. 
     A catalyst system comprising the above catalyst component, an aluminum-containing first cocatalyst and at least one silane second cocatalyst is also set forth. 
     Finally, a process for polymerizing at least one olefin utilizing the catalyst system of this disclosure is taught.

REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. Pat. application, Ser. No.521,302, filed May 9, 1990, and now U.S. Pat. No. 5,284,365 incorporatedherein by reference.

BACKGROUND OF THE DISCLOSURE

1. Field of the Invention

The polymerization of olefins using Ziegler-Natta catalysts is widelyutilized. These catalysts provide polyolefins possessing the desiredcharacteristics of these polymers in high yield. However, the use ofthese conventional catalysts are subject to important failings. Thus,new and improved catalysts are continually being sought. An importantclass of catalysts where such improvement is sought are those catalystswhich aid in the polymerization of the commercially very importantalpha-olefin, propylene.

Commonly in the polymerization of many alpha-olefins, especiallypropylene, a catalyst having a magnesium halide support is utilized.However, when polyolefins, catalytically polymerized with a magnesiumhalide supported catalyst, are processed into molded products, themolding apparatus processing the polyolefin is subject to corrosion.This corrosion is caused by the residual presence of magnesium halide inthe polymeric product. The adverse effect of this corrosion is notlimited to damaging expensive molding machinery. More importantly, thepolymeric molded article processed in this equipment is oftencharacterized by aesthetic flaws.

Another detrimental property of catalysts, conventionally used in thepolymerization of olefins, notably propylene polymers, is caused bytheir incorporation of internal electron donors. These donors areincluded in the catalyst to insure that the propylene polymer product ishighly isotactic. Those skilled in the art are aware of the criticalityof stereoregularity in propylene polymers. However, those skilled in theart are also aware that the presence of internal electron donors createsdifficulties. Unless the amount and type of electron donor compound iscarefully selected not only is the stereoregularity of the resultantpolymer deficient but, in addition, poor catalytic activity oftenresults. This detrimental effect occurs even if the amount and type ofelectron donor is properly chosen but the catalyst is formed with theelectron donor compound added in the wrong sequence.

The utilization of electron donor compounds often creates additionalproblems involving offensive odors in the final polymeric product. Thisunfortunate result obtains even if the ideal electron donor compound, inthe correct concentration, added at the proper time in the catalystformation process, is utilized. Thus, polymers polymerized in thepresence of catalysts which include an electron donor compound mustoftentimes be deashed or deodorized in order to insure the absence ofodor in the final product.

Very recently a patent application, a co-applicant of which isco-inventor of the present invention, defined a new catalyst whichsubstantially overcomes the problems discussed above. That is, a newcatalyst is therein described which produces olefinic polymers,especially propylene polymers, which possess high stereoregularity,uniform particle size distribution, good spherical morphology and highbulk density. Although this invention represents a significant advancein the art, improvements over it are highly desirable.

Although the catalyst of this new invention provides an activity inexcess of those normally obtained in propylene polymerization, it isalways desirable to improve this activity. Not only does a higheractivity producing catalyst increase the efficiency of thepolymerization process but insures a higher purity product. Thoseskilled in the art are aware that the effect of higher activity not onlyreduces the amount of catalyst required per unit weight of polymerproduct but this also translates into lower catalyst concentration inthe final polymeric product.

It is also noted that the catalyst of this recent application produces apolymer having excellent bulk density and as a corollary thereof, lowfines concentration. However, these properties, like other properties,are always subject to improvement. Those skilled in the art are awarethat the greater the bulk density, the greater the productivity of apolymerization process independent of catalyst activity. The greater thebulk density, the greater the weight of polymer produced per unit volumeof reactor. The lower the fines concentration, that is, the lower theconcentration of very small polymer particles, moreover, the lesser theproblem associated with plugging of process equipment, conduits and,especially, filters. Such plugging causes serious interruptions inproduction schedules.

Another desirable property that the significantly improved catalyst ofthe recent prior art does not fully address is the catalyst's hydrogenresponse. Those skilled in the olefin polymerization art are aware thatvariation of hydrogen concentration in olefin polymerization reactionsaffects catalyst activity as well as polymer properties. Certaincatalysts enhance these results, others diminish them and yet othershave little effect.

The above remarks make clear the continuing need in the art for a newolefin polymer catalyst having the desirable properties consideredabove. They also establish that although recent prior art hassignificantly addressed these needs further improvements are highlydesired in the art.

2. Background of the Prior Art

Japanese Patent Publication 162,607/1983 attempts to eliminate theproblem created by halogen-containing carriers. In this disclosureinorganic oxides, such as silica, were proposed as a catalyst support.This carrier, containing no halogen, was reacted with a magnesiumdialkoxide and an electron donor, such as a carboxylic acid monoester,and a titanium halide compound.

Even if the allegations made in this disclosure of high catalyticactivity, production of a highly stereospecific polymer having a highbulk density and narrow particle size distribution were correct, theproblems associated with catalyst odor were not addressed. However,testing of this catalyst established that the catalyst provided lessthan desired activity and that the olefinic polymer product was wantingin stereoregularity and particle size distribution.

A more recent disclosure, U.S. Pat. No. 4,595,735, provides a catalyticcomponent for the polymerization of olefins prepared by contacting amagnesium alkoxide, a halogenated hydrocarbon, a halogenated silane anda titanium compound. It is emphasized that this catalyst, useful in thepolymerization of ethylene homopolymers and copolymers, incorporates ahalogenated hydrocarbon. This catalyst is not only principally directedat the polymerization of ethylene polymers but, significantly,emphasizes the formation of high melt index polymers. Those skilled inthe art are aware that however useful this catalyst is in ethylenicpolymer applications, its application to propylene polymers isrestricted. Most propylene polymers are used in applications requiring apolymer of low melt flow rate. That is, the molecular weight of thepolymers produced in accordance with the '735 catalyst is significantlylower than that required of polypropylene.

U.S. Pat. No. 4,565,795 sets forth an olefin polymerization catalystwhich is prepared by the reaction of a chemically treated silica supportwith a dihydrocarbyl magnesium compound and a halogenated tetravalenttitanium compound. The chemical treatment of the silica support involvesthe use of a chlorinating compound, an alkanol, a silylating compound,an acid chloride or an organoboron compound. Again, this catalystincludes constituents which are adverse to the production ofstereoregular polymers, especially polypropylene. It is thus notsurprising that this catalyst is suggested for use in the polymerizationof ethylene polymers.

U.S. patent application, Ser. No. 326,708, filed Mar. 21, 1989, now U.S.Pat. No. 4,950,631, a co-inventor of which is a co-inventor of thepresent invention, now U.S. Pat. No. 4,950,631, a co-inventor addressesmany but not all of the demands required of olefin catalysts. Thiscatalyst has been discussed earlier.

U.S. Pat. No. 4,394,291 discloses a catalyst useful in thepolymerization of olefins. This catalyst involves the reaction of aGroup II metal dihalide with a transition metal compound. It is notedthat in an alternate embodiment this reaction also involves an electrondonor. This product is, in turn, reacted with an organoaluminumcompound. Finally, the product of this further reaction is reacted witha halide ion exchanging source. Such a source may be a multiplicity ofagents of which the combination of titanium tetrachloride with any oneof silicon tetrachloride, trichlorosilane, dichlorophenylsilane anddichlorodiphenylsilane is preferred.

U.S. Pat. No. 4,503,159 describes an olefin polymerization catalystformed by reacting water with a magnesium dihalide in the presence of aphase transfer catalyst and reacting this product with a benzoic acidester, an alkoxytitanium compound, an organoaluminum halide and ahalogen ion exchanging source. The preferred halogen ion exchangingsource is titanium tetrachloride or titanium tetrachloride and a siliconhalide which may be trichlorosilane and/or silicon tetrachloride.

U.S. Pat. No. 4,544,716 sets forth a similar catalyst to the '159 patentwherein, again, a halide ion exchanging source is utilized. A particularpreferred source is titanium tetrachloride, trichlorosilane and silicontetrachloride present in a molar ratio in the range of about 2.5:2:1 to4:3.5:1. The volume of these components are preferably such that thecombined volume of the trichlorosilane and silicon tetrachloride equalsthat of the titanium tetrachloride.

European patent application no. 0 115 833 discusses an olefinpolymerization catalyst in which a magnesium dihalide combined withwater is reacted with a benzoic acid ester and an alkoxytitaniumcompound to form a first catalyst component. This first component isreacted with a organoaluminum halide. The solid product of this reactionis reacted with a halide ion exchanging source. The ion exchangingsource in a preferred embodiment is titanium tetrachloride,trichlorosilane and silicon tetrachloride.

SUMMARY OF THE INVENTION

The present invention is directed to a catalyst system which, when addedto olefin polymerization reactants, produces olefin homopolymers andcopolymers of high stereoregularity. The polymeric product ofpolymerization reactions using the catalyst system of this invention ischaracterized by uniform particle size distribution, good sphericalmorphology and high bulk density. These characteristics enhance theproductivity and processability of the polymer. In addition, thecatalyst system is itself highly active, resulting in high polymerproductivity, as manifested by weight of polymer per unit weight ofcatalyst per hour.

The catalyst system of this invention is also characterized by safe andeasy preparation. Unlike the preparation of magnesium halide supportedcatalyst components, expensive ballmilling is not required. Neither areother expensive prepolymerization steps, required of magnesium halidesupported catalyst components, necessary. Because the catalyst componentincludes no halogen in the support, the product polymer has low halogencontent, significantly reducing the problems of corrosion oftentimesencountered in the processing of such polymers produced from magnesiumhalide supported catalyst components. Moreover, because the catalystcomponent retains low residual metal content, no deashing of the polymerproduct is required. Additionally, the polymerization reaction utilizingthis catalyst system is enhanced due to its outstanding activity, whichis relatively constant over long periods of time. Finally, the use ofthe subject catalyst system allows for enhanced activity and easycontrol of polymer molecular weight with the judicious addition ofhydrogen.

In accordance with the present invention a catalyst component isprovided. The catalyst component comprises the product obtained byinitially contacting silica with at least one hydrocarbon solublemagnesium compound and at least two modifying compounds. The sequence ofcontact with silica by the hydrocarbon soluble magnesium compound andthe first and second modifying compounds is random with therequirements, however, that the first modifying compound contact thesilica before the second modifying compound and that the modifyingcompounds contact the silica without interruption by contact with thehydrocarbon soluble magnesium compound. The first modifying compound isselected from the group consisting of silicon halides, boron halides,aluminum halides and mixtures thereof. The second modifying compound,which contacts the silica after the first modifying compound, isselected from the group consisting of halogenated silanes of the formulaSiH_(r) X² _(s), where X² is halogen; r is an integer of 1 to 3; and sis an integer of 1 to 3, with the proviso that the sum of r and s is 4,hydrogen halides of the formula HX³, where X³ is halogen, and mixturesthereof. The modified silica supporting magnesium is next contacted witha titanium-containing compound having the structural formula TiX¹ _(p)(OR¹)_(q) where X¹ is halogen; R¹ is hydrocarbyl; p is an integer of 1to 4; and q is 0 or an integer of 1 to 3, with the provisos that the sumof p and q is 4 and that a second titanium-containing compound havingthe formula Ti(OR)_(m) X_(n), where R is hydrocarbyl; X is halogen; m isan integer of 1 to 4; n is 0 or an integer of 1 to 3; and the sum of mand n is 4, is not utilized in the formation of the catalyst component.

In another aspect of the present invention a catalyst system isdescribed. The catalyst system comprises the above catalyst component, afirst co-catalyst component, an aluminum-containing compound, and asecond co-catalyst component, a hydrocarbylalkoxysilane.

In still another aspect of the present invention a process forpolymerizing olefins is disclosed. In this process at least one olefinis polymerized under olefin polymerization conditions utilizing thecatalyst system of the present invention, which includes the catalystcomponent of the present invention, the first co-catalyst component, analuminum-containing compound, and the second co-catalyst component, ahydrocarbylalkoxysilane.

DETAILED DESCRIPTION

The catalyst component of the present invention is prepared by initiallycontacting silica with at least one hydrocarbon soluble magnesiumcompound and at least two modifying compounds.

The silica employed in the catalyst component of the subject inventionis preferably pure but may contain minor amounts of other inorganicoxides such as alumina, titania, zirconia, magnesia and the like. Ingeneral, the silica support comprises at least 90% by weight puresilica. More preferably, the weight percentage of pure silica is atleast 95%. Most preferably, the weight percentage of pure silica is atleast 99%.

The silica utilized in the formation of the catalyst component, ispreferably defined by a surface are in the range of between about 80 m²/g. and about 300 m² /g., a median particle size of about 20 microns toabout 200 microns and a pore volume of between about 0.6 cc/g. and about3.0 cc/gram.

In a preferred embodiment the silica employed in the preparation of thecatalyst component is treated to replace hydroxyl groups on the surfaceof the silica with a surface characterized by the structural formula##STR1##

To accomplish this replacement the silica may be calcined in an inertatmosphere at a temperature of at least 150° C. Preferably, thecalcining operation involves heating the silica at a temperature in therange of between about 550° C. and about 650° C. in an inert atmosphere,preferably provided by nitrogen gas.

Another method of treating the silica used in making the catalystcomponent involves contacting the silica with a hexaalkyl disilazane. Ofthe hexaalkyl disilazanes useful in this application, hexamethyldisilazane is preferred.

Yet a third method of treating silica to replace its hydroxyl-containingsurface is to subject the silica to both treatment with a hexaalkyldisilazane and calcination. In this method, the sequence of theseprocessing steps is random. However, it is preferred that the hexaalkyldisilazane treatment precede calcination. It is also noted that in thislatter preferred embodiment calcination need only constitute exposure toa temperature of at least about 100° C., although higher temperatureexposure is certainly not detrimental.

As stated above, the silica is contacted with at least one hydrocarbonsoluble magnesium-containing compound. Hydrocarbon soluble magnesiumcompound that can be used in the preparation of the catalyst componentof this invention include dihydrocarbyloxymagnesiums,hydrocarbyloxymagnesium halides and mixtures thereof. Preferably, themagnesium compounds are dialkoxymagnesiums, alkoxymagnesium halides andmixtures thereof. Especially preferred magnesium compounds, contemplatedfor use in the preparation of the catalyst component of the presentinvention include 2methyl-1-pentyloxymagnesium chloride,pentyloxymagnesium chloride, 2-ethyl-hexyloxymagnesium chloride,di2-ethyl-1hexyloxmagnesium and mixtures thereof. Of these,2-ethyl-1-hexyloxymagnesium chloride and 2-methyl-1-pentyloxymagnesiumchloride are particularly preferred with 2-methy-1-pentyloxymagnesiummost preferred.

The contact between the silica and the soluble magnesium compound orcompounds usually occurs at a temperature in the range of between about15° C. and about 120° C. More preferably, this contact occurs at atemperature in the range of between about 50° C. and 110° C. The contactoccurs over a period of between about 30 minutes and about 4 hours.Preferably, the contact occurs over a period of between about 1 hour andabout 31/2 hours. Still more preferably, this contact occurs over aperiod of between about 11/2 hours and about 21/2 hours.

In addition to the silica contacting at least one soluble magnesiumcompound, the silica also contacts at least two modifying compounds. Thefirst of these modifying compounds is selected from the group consistingof silicon halides, having the structural formula SiX⁴ ₄, boron halides,having the structural formula BX⁵ ₃, aluminum halides having thestructural formula AlX⁶ ₃, where X⁴, X⁵ and X⁶ are the same or differentand are halogen, and mixtures thereof. Preferably, X⁴, X⁵ and X⁶ are thesame or different and are chlorine or bromine. Thus, it is preferredthat the first modifying compound be silicon tetrachloride, silicontetrabromide, boron trichloride, boron tribromide, aluminum trichloride,aluminum tribromide or mixtures thereof. It is more preferred that X⁴,X⁵ and X⁶ be chlorine. Thus, it is preferred that the first modifyingcompound be silicon tetrachloride, boron trichloride, aluminumtrichloride or mixtures thereof. Of these, silicon tetrachloride is mostpreferred.

The second modifying compound, which contacts the silica sequentiallyafter contact with the first modifying compound, is selected from thegroup consisting of a halogenated silane having the structural formulaSiH_(r) X² _(s), where X² is halogen; r is an integer of 1 to 3; and sis an integer of 1 to 3, with the proviso that the sum of r and s is 4,a hydrogen halide having the structural formula HX³, where X³ ishalogen, and mixtures thereof.

Preferably, the second modifying compound having one of the twostructural formulae given above is characterized by X² and X³ being thesame or different and being chlorine or bromine. In the preferredembodiment wherein the second modifying compound is the silane, it isfurther preferably characterized by r being an integer of 1 or 2 and sbeing an integer of 2 or 3. Still more preferably, the second modifyingcompounds are characterized by both X² and X³ being chlorine and, in thecase of the silane compound, r being 1 and s being 3.

Among the preferred second modifying compounds are trichlorosilane,tribromosilane, dichlorosilane, dibromosilane, hydrogen chloride,hydrogen bromide and mixtures thereof. Of these, trichlorosilane,hydrogen chloride and mixtures are more preferred. The use oftrichlorosilane as the second modifying compound is most preferred.

The concentrations of the first and second modifying compoundspreferably utilized in the formation of the catalyst component are suchthat the molar ratio of first to second modifying compound is in therange of between about 50:50 and about 99:1. More preferably this molarratio of the first to the second modifying compound is in the range ofbetween about 60:40 and about 95:5, respectively. Still more preferably,this molar ratio is in the range of between about 70:30 and about 92:8.Even still more preferably, this molar ratio is in the range of betweenabout 80:20 and about 90:10.

There is preferably no appreciable time duration between contact of thesilica with the first and second modifying compounds. This contact ispreferably sequential. That is, it is preferred that the first andsecond modifying compounds contact the silica in sequential order, thesecond modifying compound right after the first modifying compound. Thecontact between the silica, whether previously contacted with thehydrocarbon soluble magnesium compound or not, with the first and secondmodifying compounds, preferably occurs at a temperature in the range ofbetween about 10° C. and about 60° C. More preferably, the temperatureof contact between the silica and the modifying compounds is in therange of between about 20° C. and about 55° C. Still more preferably,this contact occurs at a temperature of between about 25° C. and about50° C. Most preferably, the contact temperature is in the range of about30° C. and about 45° C. The duration of contact is preferably betweenabout 10 minutes and about 2 hours. More preferably, the period of timeover which contact occurs is between about 20 minutes and 11/2 hours.Still more preferably, the time duration over which contact betweensilica and modifying compounds occurs is between about 30 minutes andabout 1 hour.

Although the order of contact between the silica and the magnesiumcompound and the silica and the modifying compounds is random, it isagain emphasized that the first modifying compound contacts the silicaprior to contact with the second modifying compound. It should beappreciated, however, that although the sequence of contact with silicaby the magnesium and modifying compounds is random, it is preferred thatthe silica initially contact the magnesium compound followed by contactwith the first and then the second modifying compounds.

In a preferred embodiment, the product of contact between the silica andthe hydrocarbon soluble magnesium compound and the modifying compoundsis next washed. That is, the product is washed with an organic solventto remove any organic-soluble residue. Although the organic solvent maybe any solvent in which the solid product does not dissolve, it ispreferred that the solvent be a hydrocarbon, either aliphatic oraromatic. Of these hydrocarbons, alkanes of 5 to 15 carbon atoms aremore preferred. Of these, hexane and heptane are even more preferred.Heptane is most preferred.

In the washing step the product is immersed in the solvent with stirringat ambient temperature. The solvent is thereafter removed bydecantation, siphoning or the like. This procedure may be repeated.Indeed, this washing step is preferably repeated two to four times.

The final step in the preparation of the catalyst component of thisinvention involves contacting the silica treated earlier with themagnesium-containing compound and the modifying compounds, whetherwashed or unwashed, with a titanium-containing compound having thestructural formula TiX¹ _(p) (OR¹)_(q) where X¹ is halogen, R¹ ishydrocarbyl; p is an integer of 1 to 4; and q is 0 or an integer of 1 to3 with the proviso that the sum of p and q is 4.

The catalyst component of this invention is further characterized by thelimitation that a second titanium-containing compound having thestructural formula Ti(OR)_(m) X_(n), where R is hydrocarbyl; X ishalogen; m is an integer of 1 to 4; and n is 0 or an integer of 1 to 3,with the proviso that the sum of m and n is 4, is not employed in itsformation. A preferred further limitation is that thetitanium-containing compound utilized in the formation of the catalystcomponent, the aforementioned compound having the structural formulaTiX¹ _(p) (OR¹)_(q), is the only titanium-containing compound utilizedin the formation of the catalyst component.

In a preferred embodiment, the titanium-containing compound ischaracterized by its above-defined structural formula where X¹ ischlorine or bromine; R is alkyl; p is an integer of 2 to 4; and q is 0,1 or 2. Compounds within the scope of this preferred embodiment,preferred for use in the preparation of the catalyst component of thepresent invention, include titanium tetrachloride, titaniumtetrabromide, methoxytitanium trichloride, methoxytitanium tribromide,ethoxytitanium trichloride, ethoxytitanium tribromide, dimethoxytitaniumdichloride, dimethoxytitanium dibromide, diethoxytitanium dichloride,diethoxytitanium dibromide and the like.

Still more preferably the titanium-containing compound is defined by pbeing an integer of 4 and q being 0. That is, the titanium compound istitanium tetrachloride or titanium tetrabromide. Of the two, titaniumtetrachloride is particularly preferred for use as thetitanium-containing compound.

The titanium-containing compound and the silica composition with whichit is contacted are exposed to a temperature in the range of betweenabout 60° C. and about 130° C. Preferably, these constituents aresubjected to a temperature in the range of between about 75° C. andabout 120° C. More preferably, the temperature of this contact is in therange of between about 85° C. and about 115° C. Most preferably, thistemperature range is between about 90° C. and about 105° C.

The time duration of this contact at elevated temperature is betweenabout 15 minutes and about 3 hours. Preferably, this time duration is inthe range of between about 30 minutes and 2 hours. More preferably, thetime of contact between the silica composition and thetitanium-containing compound is between about 45 minutes and about 11/2hours.

An optional preferred step in the formation of the catalyst componentinvolves washing of the product of contact of the silica composition andthe titanium-containing compound. The washing of this product involvesthe same process discussed above in the discussion of the washing of thesilica composition prior to treatment with the titanium-containingcompound. Thus, the use of hydrocarbon solvents of the types discussedin the preferred first washing step is preferred. It is desirable,however, in the preferred embodiment wherein the product of the titaniumcompound contact is washed, that the number of washing cycles beincreased. Thus, whereas the first washing step preferably employs abouttwo to four washing cycles, it is preferred that this second optionalwashing procedure involve about six to eight washing cycles.

It should be appreciated that all the treatment steps in the formationof the catalyst component of this invention, the contact of silica withthe hydrocarbon soluble magnesium compound, the modifying compounds andthe titanium-containing compound, involve contact between a solid,silica, and a liquid. This is because each of the compounds that arecontacted with silica are liquids or are soluble in an inert hydrocarbonsolvent under the conditions of use. As such, no ballmilling or othersolid mixing is required. This expensive and difficult operation, usualin the formation of polymerization catalysts of the prior art, is thuseliminated. Those skilled in the art are aware, in the case where ahydrocarbon solvent is employed, that the solvent may be allowed toremain with the reaction mass or can be removed by decantation,filtration, evaporation or the like.

Further observations regarding the above catalyst component formationsteps include the facts that the morphology of the polymer produced fromthis catalyst emulates the support; that the absence of any halogen inthe support aids in keeping the halogen content of the polymer producedtherefrom low; that the relatively low concentrations of titanium andmagnesium on the silica support also tends to keep polymeric magnesiumand titanium concentrations at similarly low levels; that thepreparation of the catalyst component of the present invention isconducted at moderate temperature, preferably in the range of betweenabout 0° C. and 100° C.; and that even though this catalyst componentdoes not need an electron donor for excellent isotacticity it ispossible to use one or more of them if desired.

Another aspect of the present invention is directed to a catalystsystem. The catalyst system of this invention comprises the catalystcomponent described in detail above, a first co-catalyst component and asecond co-catalyst component.

The first co-catalyst component of the catalyst system is analuminum-containing compound. The aluminum-containing compound ispreferably an alkylaluminum-containing compound. Thealkylaluminum-containing compound is preferably a trialkylaluminum,alkylaluminum halide or mixtures thereof. More preferably, theco-catalyst is a trialkylaluminum. Of the trialkylaluminums,triethylaluminum and tri-n-propylaluminum are particularly preferredwith triethylaluminum most preferred.

The second co-catalyst component of the catalyst system is preferably atleast one silane compound Preferably, the silane compound is ahydrocarbylalkoxysilane. Preferred hydrocarbylalkoxysilanes includehydrocarbyltrialkoxysilanes, dihydrocarbyldialkoxysilanes andtrihydrocarbylalkoxysilanes. Of these, the dihydrocarbyldialkoxysilanesand the trihydrocarbylalkoxysilanes are more preferred with thedihydrocarbyldialkoxysilanes most preferred.

The hydrocarbyl constituent of the silane second co-catalyst componentis preferably phenyl, alkaryl, or C₁ -C₁₀ linear, branched or cyclicalkyl. The preferred alkoxy constituent is one containing one to sixcarbon atoms.

Of the dihydrocarbyldialkoxysilanes, diisopropyldimethoxysilane andisobutylisopropyldimethoxysilane are particularly preferred withdiisopropyldimethoxysilane most preferred.

In still another aspect of the present invention a process forpolymerizing an olefin is set forth. This process comprises polymerizingat least one olefin under olefin polymerization conditions in thepresence of the catalyst system of the present invention. That is, inthe presence of the catalyst component of the subject invention, thefirst co-catalyst component and the second co-catalyst component.

In a particularly preferred embodiment of this aspect of the presentinvention, the olefin polymerized is propylene. In this preferredembodiment, polymerization occurs at a temperature in the range ofbetween about 35° C. and about 100° C. More preferably, the temperatureof this reaction is in the range of about 50° C. and about 80° C. Thepressure of the propylene polymerization reaction is in the range ofbetween about 300 psig and about 600 psig, more preferably, betweenabout 400 psig and about 500 psig. In a preferred embodiment thepropylene polymerization occurs in the presence of hydrogen gas.

The following examples are given to illustrate the scope of thisinvention. Because these examples are given for illustrative purposesonly, the invention embodied therein should not be limited thereto.

EXAMPLE 1 Preparation of Catalyst Component

A master batch of 2-methyl-1-pentyloxymagnesium chloride was prepared bycharging Davison [trademark] 948 silica treated with hexamethyldisilazane (6 lb) into a ribbon blender. The contents were heated undera nitrogen atmosphere at a temperature of between 90° and 100° C. forone hour. After the heating step the blender and its silica contentswere cooled to room temperature.

To the cooled silica in the, blender was added a solution of 17.2 wt%2-methyl-1-pentyloxymagnesium chloride in heptane (16.8 lb). Stirringwas commenced and the contents of the blender were heated under anitrogen atmosphere for 2 to 3 hours at 100° C. At the conclusion ofthis period 67% by weight of the solvent was evaporated leaving a dry,free flowing solid product. The solid product was analyzed and found topossess a chemical constituency as follows:

    ______________________________________                                        Constituent       Wt %                                                        ______________________________________                                        Si                47.9                                                        Mg                4.67                                                        Cl                15.8                                                        Hydrocarbon Solv. 31.63                                                       ______________________________________                                    

This master batch was stored in a water-free and oxygen-freeenvironment.

2-Methyl-1-pentyloxymagnesium chloride master batch (8 gm.) wasintroduced into a four-necked round bottom 250 ml. flask equipped with apaddle stirrer and a nitrogen purge. Heptane (10 ml.) was added to theflask and stirring was commenced. To this suspension was added silicontetrachloride (2.55 ml., 20 mmol.) followed immediately bytrichlorosilane (0.45 ml., 4 mmol.). The contents of the flask werestirred for 40 minutes at 40° C. The thus heated contents were cooled toroom temperature and washed with heptane (70 ml.). This washing step wasrepeated twice for a total of three times.

The washed product was returned to the flask and was contacted withtitanium tetrachloride (10 ml., 90 mmol.) at room temperature. Thecontents were heated for 1 hour at 90° C. The solid product resultingtherefrom was washed with heptane (80 ml.). This washing step wasrepeated five times for a total of six times. The washed solid productwas dried with nitrogen gas, free of water and oxygen.

The product was analyzed by X-ray fluorescence and was found to possesstitanium, magnesium, silica and chlorine in the concentrations set forthin the Table.

COMPARATIVE EXAMPLE 1 Preparation of Catalyst Component

Example 1 was identically repeated but for the addition of the step ofcontacting the solid product washed three times with heptane with a 50%by volume solution of titanium tetracresylate in heptane (1.2 ml., 2mmol.).

This step was included prior to contact with titanium tetrachloride. Itis noted that the contact with the titanium tetrachloride was added tothe solid product 5 minutes after contact with the titaniumtetracresylate.

The product of this example was analyzed by X-ray fluorescence and itstitanium, magnesium, silica and chlorine constituency determined. Theseconcentrations are reported in the Table.

EXAMPLE 2 Polymerization of Propylene

The catalyst component (0.02 g.) prepared in accordance with Example 1was charged into a 1-liter Parr [trademark] reactor withtriethylaluminum (TEAL) and isobutylisopropyldimethoxysilane (IBIP). Theconcentrations of TEAL and IBIP introduced into the reactor were suchthat the molar ratio of TEAL to IBIP to catalyst component made inaccordance with Example 1 was 80:8:1.

To the catalyst system contents of the reactor was added heptane (20ml). Thereupon, hydrogen gas (400 ml.) and then propylene (325 g.) wasadded thereto. The contents were then heated to 70° C. for 1 hour at apressure of 460 psig.

The polypropylene product of this polymerization reaction was weighedand analyzed. The results of these observations are included in theTable.

It is noted that the critical % hydrocarbon insoluble property of thepolypropylene product reported in the Table is determined by a procedurein which a ground polypropylene sample passing through a 20 mesh screen(1 g. to 1.5 g.) is dried in a vacuum oven for 30 minutes at 100° C. Thedried sample, disposed in a thimble, whose exact weight is determined,is dried in a desiccator and cooled to room temperature. The thimblecontaining the ground polypropylene sample is weighed and then placed inan extraction flask provided with about 150 ml. heptane and some boilingchips. The flask is thereupon connected to a condensor. With coolingwater flowing, the condensor is heated. After two hours of boiling theheptane solvent, heating is stopped and the thimble is removed from thecondensor flask. The thimble and its polypropylene contents are againheated in a vacuum oven at 100° C. for 30 minutes and thereafter cooledto room temperature in a desiccator. The thimble and its contents areagain weighed. The weight of the polypropylene after reflux divided byits weight prior to reflux represents % hydrocarbon insoluble.

COMPARATIVE EXAMPLE 2 Polymerization of Propylene

The polymerization of Example 2 was identically repeated but for thesubstitution of a like charge of the catalyst component of ComparativeExample 1 for the catalyst component of Example 1 utilized in Example 2.

The results of this example are included in the Table.

                                      TABLE                                       __________________________________________________________________________                            Polymerization Results                                Cat. Comp. of                                                                         Catalyst Component.sup.1                                                                 Poly. of                                                                           Activity  Polypropylene Characteristics               Ex. No. Ti                                                                              Mg Si Cl Ex. No.                                                                            PP/g.Cat                                                                           Ti, ppm                                                                            % Hydrocarbon Insol.                                                                     Bulk Den, lb/ft.sup.3            __________________________________________________________________________    1       5.3                                                                             3.9                                                                              47.3                                                                             13.1                                                                             2     7,500                                                                             7.9  98.0       25.6                             CE1     4.5                                                                             3.6                                                                              47.1                                                                             20.5                                                                             CE2  10,000                                                                             4.4  95.9       23.0                             __________________________________________________________________________     Footnotes:                                                                    .sup.1 Reported as % by Wt.                                              

DISCUSSION OF EXAMPLES

An analysis of the results of the examples establish that althoughcatalyst activity is reduced in the absence of titanium tetracresylate,the polypropylene produced in accordance with the invention of thepresent application has marginally improved crystallinity. This ismanifested by the hydrocarbon insolubility of the polypropylene. Asthose skilled in the art are aware, the higher the percent hydrocarboninsoluble, the higher is the degree of crystallinity of thepolypropylene. The higher the degree of crystallinity the more usefulthe polymer in certain processing schemes and in upscale applications.

For example, polypropylene having a higher degree of crystallinity ismuch more readily injection molded. Similarly, impact resistance ofmolded polypropylene is very sensitive to crystallinity. Impactresistance, critical in the use of polypropylene in engineering resinapplications, such as automobile bumpers, is directly dependent upon thedegree of crystallinity.

The above embodiments and examples are given to illustrate the scope andspirit of the instant invention. These embodiments and examples willmake apparent, to those skilled in the art, other embodiments andexamples. These other embodiments and examples are within thecontemplation of the present invention. Therefore, the present inventionshould be limited only by the appended claims.

WHAT IS CLAIMED IS:
 1. A catalyst component comprising the productprepared by the steps of:(a) contacting silica with components(1) atleast one hydrocarbon soluble magnesium-containing compound; and (2) afirst modifying compound selected from the group consisting of siliconhalide; boron halides, aluminum halides and mixtures thereof followed bya second modifying compound selected from the group consisting of asilane of the formula SiH_(r) X² _(s), where X² is halogen; r is aninteger of 1 to 3; and s is an integer of 1 to 3, with the proviso thatthe sum of r and s is 4, hydrogen halides having the structural formulaHX³, where X³ is halogen, and mixtures thereof, said sequence of contactof silica with said components (1) and (2) being random; and (b)contacting the product of step (a) with a titanium-containing compoundhaving the structural formula TiX¹ _(p) (OR¹)_(q), where X¹ is halogen;R¹ is hydrocarbyl; p is an integer of 1 to 4; q is 0 or an integer of 1to 3, with the provisos that the sum of p and q is 4 and that a secondtitanium-containing compound having the structural formula Ti(OR)_(m)X_(n), where R is hydrocarbyl; X is halogen; m is an integer of 1 to 4;n is 0 or an integer of 1 to 3; and the sum of m and n is 4, is notutilized in the formation of said catalyst component.
 2. A catalystcomponent in accordance with claim 1 wherein said silica is at least 90%pure silica having a surface area of between about 80 m² /g. and about300 m² /g., a medium particle size of between about 20 microns and about200 microns and a pore volume of between about 0.6 cc/g. and about 3.0cc/g.
 3. A catalyst component in accordance with claim 1 wherein saidsilica is pretreated, prior to step (a), to replace surface hydroxylwith a surface characterized by the structural formula ##STR2##
 4. Acatalyst component in accordance with claim 3 wherein said silicapretreatment comprises calcining said silica at a temperature of atleast about 150° C. in an inert atmosphere.
 5. A catalyst component inaccordance with claim 3 wherein said silica pretreatment comprisescontacting said silica with a hexaalkyl disilazane.
 6. A catalystcomponent in accordance with claim 3 wherein said silica pretreatmentcomprises (a) contacting said silica with a hexaalkyl disilazane and (b)calcining said silica at a temperature of at least about 100° C. in aninert atmosphere, said steps (a) and (b) occurring in random order.
 7. Acatalyst component in accordance with claim 1 wherein said hydrocarbonsoluble magnesium compound is selected from the group consisting ofdihydrocarbyloxymagnesiums, hydrocarbyloxymagnesium halides and mixturesthereof.
 8. A catalyst component in accordance with claim 1 wherein saidfirst modifying compound is selected from the group consisting ofsilicon tetrachloride, boron trichloride and aluminum trichloride.
 9. Acatalyst component in accordance with claim 1 wherein said secondmodifying compound or compounds are characterized by X² and X³ being thesame or different and being chlorine or bromine; r being 1 or 2; and sbeing 2 or
 3. 10. A catalyst component in accordance with claim 1wherein said titanium-containing compound is characterized by X¹ beingchlorine or bromine; R¹ being alkyl; p being an integer of 2 to 4; and qbeing 0, 1 or
 2. 11. A catalyst component in accordance with claim 1wherein said silica in step (a) contacts component (1) prior to contactwith component (2).
 12. A catalyst component in accordance with claim 1wherein said first modifying compound and said second modifying compoundcontact said silica in an amount such that the molar ratio of said firstmodifying compound to said second modifying compound is in the range ofbetween about 50:50 and about 99:1.
 13. A catalyst component inaccordance with claim 1 including the step of washing said product ofstep (a) with an organic solvent prior to said step (b).
 14. A catalystcomponent in accordance with claim 1 including the step of washing saidproduct of step (b) with an organic solvent.
 15. A catalyst component inaccordance with claim 1 wherein said contact between said silica andsaid hydrocarbon soluble magnesium compound of step (a) occurs at atemperature in the range of between about 15° C. and about 120° C. overa period in the range of between about 30 minutes and 4 hours.
 16. Acatalyst component in accordance with claim 1 wherein said contactbetween said silica and said first and second modifying compounds ofstep (a) occurs at a temperature of between about 10° C. and about 60°C. over a period of between about 10 minutes and about 2 hours.
 17. Acatalyst component in accordance with claim 1 wherein said step (b)occurs at a temperature in the range of between about 60° C. and about130° C. over a period in the range of between 15 minutes and about 3hours.
 18. A catalyst component comprising the product prepared by thesteps of:(a) contacting silica, pretreated to replace surface hydroxylgroups with a-surface characterized by the structural formula ##STR3##with components: (1) a compound selected from the group consisting of adihydrocarbyloxymagnesium, a hydrocarbyloxymagnesium halide and mixturesthereof; and(2) a first modifying compound selected from the groupconsisting of a silicon tetrahalide, a boron trihalide and an aluminumtrihalide followed by a second modifying compound selected from thegroup consisting of halogenated silane having the structural formulaSiH_(r) X² _(s), where X² is halogen; r is an integer of 1 or 2; and sis an integer of 2 or 3, with the proviso that the sum of r and s is 4,a hydrogen halide having the structural formula HX³, where X³ ischlorine or bromine, and mixtures thereof; said first and said secondmodifying compounds contacting said silica in an amount such that themolar ratio of said first to said second modifying compound is in therange of between about 50:50 and about 99:1, said sequence of contact ofsaid components (1) and (2) with silica being random; and (b) contactingthe product of step (a) with a titanium compound having the structuralformula TiX¹ _(p) (OR¹)_(q), where X¹ is chlorine or bromine; R¹ isalkyl; p is an integer of 2 to 4; and q is 0, 1 or 2, with the provisosthat the sum of p and q is 4 and that a second titanium-containingcompound having the structural formula Ti(OR)_(m) X_(n), where R ishydrocarbyl; X is halogen; m is an integer of 1 to 4; n is 0 or aninteger of 1 to 3; and the sum of m and n is 4, is not utilized in theformation of said catalyst component.
 19. A catalyst component inaccordance with claim 18 wherein said silica is pretreated by:(a)calcining said silica at a temperature of at least about 150° C. in aninert atmosphere, (b) treating said silica with a hexaalkyl disilazaneor (c) in random order, calcining said silica at a temperature of atleast about 100° C. in an inert atmosphere and treating said silica witha hexaalkyl disilazane.
 20. A catalyst component in accordance withclaim 19 wherein said calcining step (a) occurs at a temperature in therange of between about 550° C. and about 650° C. in a nitrogenatmosphere, and said hexaalkyl disilazane of steps (b) and (c) ishexamethyl disilazane.
 21. A catalyst component in accordance with claim18 wherein said component (1) is a hydrocarbyloxymagnesium halide.
 22. Acatalyst component in accordance with claim 21 wherein saidhydrocarbyloxymagnesium halide is selected from the group consisting of2-methylpentyloxymagnesium chloride and 2-ethylhexyloxymagnesiumchloride.
 23. A catalyst component in accordance with claim 22 whereinsaid first modifying compound of component (2) is silicon tetrachloride.24. A catalyst component in accordance with claim 23 wherein said secondmodifying compound of component (2) is selected from the groupconsisting of dichlorosilane, trichlorosilane, hydrogen chloride andmixtures thereof
 25. A catalyst component in accordance with claim 24wherein said second modifying compound of component (2) istrichlorosilane.
 26. A catalyst component in accordance with claim 25wherein said molar ratio of component (1) to component (2) is in therange of between about 60:40 and about 95:5.
 27. A catalyst component inaccordance with claim 26 wherein said sequence of contact of silica withcomponents (1) and (2) in step (a) is component (1) followed bycomponent (2).
 28. A catalyst component in accordance with claim 25wherein said titanium-containing compound is characterized by p being 4and n being
 0. 29. A catalyst component in accordance with claim 28wherein said titanium-containing compound is titanium tetrachloride. 30.A catalyst component in accordance with claim 18 wherein said contactbetween said silica and said hydrocarbyloxymagnesium halide of step (a)occurs at a temperature of between about 50° C. and about 110° C. over aperiod of between about 1 hour and about 31/2 hours.
 31. A catalystcomponent in accordance with claim 30 wherein said contact between saidsilica and said first and said second modifying compounds of step (a)occurs at a temperature in the range of between about 20° C. and about55° C over a period of between about 20 minutes and about 11/2 hours.32. A catalyst component in accordance with claim 31 wherein said step(b) occurs at a temperature in the range of between about 75° C. andabout 120° C. over a period in the range of between about 30 minutes andabout 4 hours.
 33. A catalyst component in accordance with claim 32comprising the step of washing the product of step (a) with an alkanecontaining 5 to 15 carbon atoms prior to said step (b).
 34. A catalystcomponent in accordance with claim 33 comprising the step of washing theproduct of step (b) with an alkane having 5 to 15 carbon atoms.
 35. Acatalyst component comprising the product prepared by the steps of:(a)contacting silica, said silica characterized by a surface area ofbetween about 80 m² /g. and about 300 m² /g., a median particle size ofbetween about 20 microns and about 200 microns and a pore volume ofbetween about 0.6 cc/g. and about 3.0 cc/g., with2-methylpentyloxymagnesium chloride; (b) contacting the product of step(a) with silicon tetrachloride; (c) contacting the product of step (b)with trichlorosilane, with the proviso that the concentration of saidsilicon tetrachloride and said trichlorosilane contacting said productsof steps (a) and (b), respectively, is such that the molar ratio of saidsilicon tetrachloride to said trichlorosilane is in the range of betweenabout 70:30 and about 92:8; (d) contacting the product of step (c) withtitanium tetrachloride, with the proviso that titanium tetrachloride isthe sole titanium-containing compound utilized in the formation of saidcatalyst component.
 36. A catalyst component in accordance with claim 35wherein said step (a) occurs at a temperature in the range of betweenabout 50° C. and about 110° C. for a period of between about 11/2 hoursand about 21/2 hours.
 37. A catalyst component in accordance with claim36 wherein said step (b) occurs at ambient temperature followedimmediately by said step (c) conducted at a temperature in the range ofbetween about 25° C. and about 50° C over a period of between about 30minutes and about 1 hour.
 38. A catalyst component in accordance withclaim 37 wherein said step (d) is conducted at between about 85° C andabout 115° C. over a period of between about 45 minutes and about 11/2hours.
 39. A catalyst component in accordance with claim 38 comprisingthe washing of the product of step (c) with hexane or heptane prior tosaid step (d).
 40. A catalyst component in accordance with claim 39comprising the washing of said product of step (d) with hexane orheptane.
 41. A catalyst system comprising said catalyst component ofclaim 1, an aluminum-containing compound first co-catalyst component andat least one silane second cocatalyst component.
 42. A catalyst systemcomprising said catalyst component of claim 18, analkylaluminum-containing compound first co-catalyst component and atleast one hydrocarbylalkoxysilane second co-catalyst component.
 43. Acatalyst system comprising said catalyst component of claim 35, acompound selected from the group consisting of triethylaluminum andtri-n-propylaluminum and isobutylisopropyldimethoxysilane.